Biomarker for ovarian cancer CTAP3-related proteins

ABSTRACT

The present invention provides a protein-based biomarker that is useful in qualifying ovarian cancer status in a patient. In particular, the biomarker of this invention is useful to classify a subject sample as ovarian cancer or non-ovarian cancer. The biomarker can be detected by SELDI mass spectrometry.

RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.11/473,280, filed Jun. 21, 2006, which claims the benefit of U.S.Provisional Application No. 60/693,324, filed Jun. 22, 2005. The entirecontents of each of the afforementioned applications is herebyincorporated herein by reference.

FIELD OF THE INVENTION

The invention provides for a biomarker important in the detection ofovarian cancer. The marker was identified by distinguishing the serumprotein profile in ovarian cancer patients from healthy individualsusing SELDI analysis. The present invention relates the biomarker to asystem and method in which the biomarker is used for the qualificationof ovarian cancer status. The present invention also identifies abiomarker as a known protein, CTAP3.

BACKGROUND OF THE INVENTION

Ovarian cancer is among the most lethal gynecologic malignancies indeveloped countries Annually in the United States alone, approximately23,000 women are diagnosed with the disease and almost 14,000 women diefrom it. (Jamal, A., et al., CA Cancer J. Clin, 2002; 52:23-47). Despiteprogress in cancer therapy, ovarian cancer mortality has remainedvirtually unchanged over the past two decades. (Id.) Given the steepsurvival gradient relative to the stage at which the disease isdiagnosed, early detection remains the most important factor inimproving long-term survival of ovarian cancer patients.

The poor prognosis of ovarian cancer diagnosed at late stages, the costand risk associated with confirmatory diagnostic procedures, and itsrelatively low prevalence in the general population together poseextremely stringent requirements on the sensitivity and specificity of atest for it to be used for screening for ovarian cancer in the generalpopulation.

The identification of tumor markers suitable for the early detection anddiagnosis of cancer holds great promise to improve the clinical outcomeof patients. It is especially important for patients presenting withvague or no symptoms or with tumors that are relatively inaccessible tophysical examination. Despite considerable effort directed at earlydetection, no cost effective screening tests have been developed (PaleyP J., Curr Opin Oncol, 2001; 13(5):399-402) and women generally presentwith disseminated disease at diagnosis. (Ozols R F, et al., Epithelialovarian cancer. In: Hoskins W J, Perez C A, Young R C, editors.Principles and Practice of Gynecologic Oncology. 3rd ed. Philadelphia:Lippincott, Williams and Wilkins; 2000. p. 981-1057).

The best-characterized tumor marker, CA125, is negative in approximately30-40% of stage I ovarian carcinomas and its levels are elevated in avariety of benign diseases. (Meyer T, et al., Br J Cancer, 2000;82(9):1535-8; Buamah P., J Surg Oncol, 2000; 75(4):264-5; Tuxen M K, etal., Cancer Treat Rev, 1995; 21(3):215-45). Its use as apopulation-based screening tool for early detection and diagnosis ofovarian cancer is hindered by its low sensitivity and specificity.(MacDonald N D, et al., Eur J Obstet Gynecol Reprod Biol, 1999;82(2):155-7; Jacobs I, et al., Hum Reprod, 1989; 4(1):1-12; Shih I-M, etal., Tumor markers in ovarian cancer. In: Diamandis E P, Fritsche, H.,Lilja, H., Chan, D. W., and Schwartz, M., editor. Tumor markersphysiology, pathobiology, technology and clinical applications.Philadelphia: AACC Press; in press). Although pelvic and more recentlyvaginal sonography has been used to screen high-risk patients, neithertechnique has the sufficient sensitivity and specificity to be appliedto the general population. (MacDonald N D, et al., supra). Recentefforts in using CA125 in combination with additional tumor markers(Woolas R P X F, et al., J Natl Cancer Inst, 1993; 85(21):1748-51;Woolas R P, et al., Gynecol Oncol, 1995; 59(1):111-6; Zhang Z, et al.,Gynecol Oncol, 1999; 73(1):56-61; Zhang Z, et al., Use of MultipleMarkers to Detect Stage I Epithelial ovarian cancers: Neural NetworkAnalysis Improves Performance. American Society of Clinical Oncology2001; Annual Meeting, Abstract) in a longitudinal risk of cancer model(Skates S J, et al., Cancer, 1995; 76(10 Suppl):2004-10), and in tandemwith ultrasound as a second line test (Jacobs I D A, et al., Br Med J,1993; 306(6884):1030-34; Menon U T A, et al., British Journal ofObstetrics and Gynecology, 2000; 107(2):165-69) have shown promisingresults in improving overall test specificity, which is critical for adisease such as ovarian cancer that has a relatively low prevalence.

Due to the dismal prognosis of late stage ovarian cancer, it is thegeneral consensus that a physician will accept a test with a minimalpositive predictive value of 10%. (Bast, R. C., et al., Cancer Treatmentand Research, 2002; 107:61-97). Extending this to the generalpopulation, a general screening test would require a sensitivity greaterthan 70% and a specificity of 99.6%. Currently, none of the existingserologic markers, such as CA125, CA72-4, or M-CSF, individuallydelivers such a performance. (Bast, R. C., et al., Int J Biol Markers,1998; 13:179-87).

Thus, there is a critical need for new serological markers thatindividually or in combination with other markers or diagnosticmodalities deliver the required sensitivity and specificity for earlydetection of ovarian cancer. (Bast R C, et al., Early detection ofovarian cancer: promise and reality. ovarian cancer: ISIS Medical MediaLtd., Oxford, UK; 2001. in press). Without an acceptable screening test,early detection remains the most critical factor in improving long-termsurvival of patients with ovarian cancer.

Thus, it is desirable to have a reliable and accurate method ofdetermining the ovarian cancer status in patients, the results of whichcan then be used to manage subject treatment.

SUMMARY OF THE INVENTION

It has been found that CTAP3 is up-regulated in the serum of patientswith ovarian cancer. Accordingly, the level of CTAP3 is useful as abiomarker in making a determination of ovarian cancer in a subject.Likewise, CTAP3-related proteins are useful as biomarkers for making adetermination of ovarian cancer in a subject

The present invention provides sensitive and quick methods and kits thatare useful for determining the ovarian cancer status by measuring one ormore specific biomarkers, e.g., CTAP3-related molecules such as CTAP3.The measurement of this marker in patient samples provides informationthat diagnosticians can correlate with a probable diagnosis of humancancer or a negative diagnosis (e.g., normal or disease-free). Themarker is characterized by molecular weight and its known proteinidentity. The marker can be resolved from other proteins in a sample byusing a variety of fractionation techniques, e.g., chromatographicseparation coupled with mass spectrometry, protein capture usingimmobilized antibodies or by traditional immunoassays. In preferredembodiments, the method of resolution involves Surface-Enhanced LaserDesorption/Ionization (“SELDI”) mass spectrometry, in which the surfaceof the mass spectrometry probe comprises adsorbents that bind themarkers.

The present invention provides a method of qualifying ovarian cancerstatus in a subject comprising measuring at least one biomarkerincluding a CTAP3-related peptide, e.g., CTAP3, in a biological samplefrom the subject; and (b) correlating the measurement with ovariancancer status. In certain methods, the measuring step comprisesdetecting the presence or absence of the marker in the sample. In othermethods, the measuring step comprises quantifying the amount of markerin the sample. In other methods, the measuring step comprises qualifyingthe type of biomarker in the sample.

The invention also relates to methods wherein the measuring stepcomprises: providing a subject sample of blood or a blood derivative;fractionating proteins in the sample on an anion exchange resin andcollecting fractions that contain a CTAP3-related peptide, e.g., CTAP3,from the fractions on a surface of a substrate comprising capturereagents that bind this protein biomarkers. The blood derivative is,e.g., serum or plasma. In preferred embodiments, the substrate is aSELDI probe comprising an IMAC copper surface and wherein the proteinbiomarkers are detected by SELDI. In other embodiments, the substrate isa SELDI probe comprising bio specific affinity reagents that bind, forexample, CTAP3 and wherein the protein biomarkers are detected by SELDI.In other embodiments, the substrate is a microtiter plate comprising biospecific affinity reagents that bind CTAP3 and the protein biomarker isdetected by immunoassay.

In certain embodiments, the methods further comprise managing subjecttreatment based on the status determined by the method. For example, ifthe result of the methods of the present invention is inconclusive orthere is reason that confirmation of status is necessary, the physicianmay order more tests. Alternatively, if the status indicates thatsurgery is appropriate, the physician may schedule the patient forsurgery. Furthermore, if the results show that treatment has beensuccessful, no further management may be necessary.

The invention also provides for such methods where the CTAP3-relatedbiomarker is measured again after subject management, i.e., treatment.In these instances, the step of managing subject treatment is thenrepeated and/or altered depending on the result obtained. In furtherembodiments, the measurement is correlated with disease progression.

The term “ovarian cancer status” refers to the status of the disease inthe patient. Examples of types of ovarian cancer statuses include, butare not limited to, the subject's risk of cancer, the presence orabsence of disease, the stage of disease in a patient, and theeffectiveness of treatment of disease. Other statuses and degrees ofeach status are known in the art.

In certain preferred embodiments, the method for qualifying ovariancancer status further comprises measuring and correlating at least onebiomarker selected from the group consisting of CA125, transferrin,haptoglobin, ApoA1, transthyretin, ITIH4 internal fragment, beta2-microglobulin, hepcidin, prostatin, osteopontin, esoinophil-derivedneurotoxin, leptin, prolactin, IGF-II, hemoglobin and modified formsthereof with ovarian cancer status.

In other preferred embodiments, the method for qualifying ovarian cancerstatus further comprises measuring and correlating at least onebiomarker selected from the group consisting of CA125 II, CA15-3,CA19-9, CA72-4, CA 195, tumor associated trypsin inhibitor (TATI), CEA,placental alkaline phosphatase (PLAP), Sialyl TN, galactosyltransferase,macrophage colony stimulating factor (M-CSF, CSF-1), lysophosphatidicacid (LPA), 110 kD component of the extracellular domain of theepidermal growth factor receptor (p110EGFR), tissue kallikreins, e.g.,kallikrein 6 and kallikrein 10 (NES-1), prostasin, HE4, creatine kinaseB (CKB), LASA, HER-2/neu, urinary gonadotropin peptide, Dianon NB 70/K,Tissue peptide antigen (TPA), SMRP, osteopontin, and haptoglobin,leptin, prolactin, insulin-like growth factor I and insulin-like growthfactor II with ovarian cancer status.

In one embodiment, the invention provides methods that comprisemeasuring the CTAP3 marker in conjunction with measuring CA125 or CA125II in a biological sample from a subject and correlating the coordinatedmeasurement with ovarian cancer status. We have found that measurementof CTAP3 in conjunction or combination with CA125 can provide enhancedresults (e.g., enhanced discrimination or detection) than measurement ofeither marker alone.

In another embodiment, the invention provides methods that comprisemeasuring the CTAP3 marker in a biological sample from a subject andcorrelating the measurement with ovarian cancer status, wherein thestatus is borderline ovarian cancer versus invasive ovarian cancer. Wehave found that CTAP3 can discriminate between borderline ovarian cancerversus invasive ovarian cancer

The CTAP3-related biomarkers of the invention can be characterized inone or more of several respects. In particular, in one aspect, thismarker is characterized by molecular weight under the conditionsspecified herein, particularly as determined by mass spectral analysis.In another aspect, the marker can be characterized by features of themarker's mass spectral signature such as size (including area) and/orshape of the marker's spectral peaks, features including proximity, sizeand shape of neighboring peaks, etc. In yet another aspect, the markercan be characterized by affinity binding characteristics, particularlyability to binding to an IMAC copper adsorbent under specifiedconditions, however, other metals, e.g., nickel, may also be used. Inpreferred embodiments, marker of the invention may be characterized byeach of such aspects, i.e. molecular weight, mass spectral signature andIMAC-Cu absorbent binding.

For the mass values of the marker disclosed herein, the mass accuracy ofthe spectral instrument is considered to be about within +/−0.15 percentof the disclosed molecular weight value. Additionally, to suchrecognized accuracy variations of the instrument, the spectral massdetermination can vary within resolution limits of from about 400 to1000 m/dm, where m is mass and dm is the mass spectral peak width at 0.5peak height. Those mass accuracy and resolution variances associatedwith the mass spectral instrument and operation thereof are reflected inthe use of the term “about” in the disclosure of the mass of the markerI. It is also intended that such mass accuracy and resolution variancesand thus meaning of the term “about” with respect to the markersdisclosed herein is inclusive of variants of the marker as may exist dueto sex, genotype and/or ethnicity of the subject and the particularcancer or origin or stage thereof.

The present invention further provides a method of qualifying ovariancancer status in a subject comprising (a) measuring the CTAP3 biomarkerin a sample from the subject, and (b) correlating the measurement withovarian cancer status. In certain methods, the measuring step comprisesdetecting the presence or absence of the marker in the sample. In othermethods, the measuring step comprises quantifying the amount of markerin the sample.

The accuracy of a diagnostic test is characterized by a ReceiverOperating Characteristic curve (“ROC curve”). An ROC is a plot of thetrue positive rate against the false positive rate for the differentpossible cutpoints of a diagnostic test. An ROC curve shows therelationship between sensitivity and specificity. That is, an increasein sensitivity will be accompanied by a decrease in specificity. Thecloser the curve follows the left axis and then the top edge of the ROCspace, the more accurate the test. Conversely, the closer the curvecomes to the 45-degree diagonal of the ROC graph, the less accurate thetest. The area under the ROC is a measure of test accuracy. The accuracyof the test depends on how well the test separates the group beingtested into those with and without the disease in question. An areaunder the curve (referred to as “AUC”) of 1 represents a perfect test,while an area of 0.5 represents a less useful test. Thus, biomarker anddiagnostic methods of the present invention have an AUC greater than0.50, more preferred tests have an AUC greater than 0.60, more preferredtests have an AUC greater than 0.70.

Preferred methods of measuring biomarkers include use of a biochiparray. Biochip arrays useful in the invention include protein andnucleic acid arrays. One or more markers are captured on the biochiparray and subjected to laser ionization to detect the molecular weightof the marker. Analysis of the marker is, for example, by molecularweight of the marker against a threshold intensity that is normalizedagainst total ion current. Preferably, logarithmic transformation isused for reducing peak intensity ranges to limit the number of markersdetected.

In preferred methods of the present invention, the step of correlatingthe measurement of the biomarkers with ovarian cancer status isperformed by a software classification algorithm. Preferably, data isgenerated on immobilized subject samples on a biochip array, bysubjecting said biochip array to laser ionization and detectingintensity of signal for mass/charge ratio; and, transforming the datainto computer readable form; and executing an algorithm that classifiesthe data according to user input parameters, for detecting signals thatrepresent marker present in ovarian cancer patients and are lacking innon-cancer subject controls.

Preferably the biochip surfaces are, for example, ionic, anionic,comprised of immobilized nickel ions, comprised of a mixture of positiveand negative ions, comprised of one or more antibodies, single or doublestranded nucleic acids, proteins, peptides or fragments thereof, aminoacid probes, or phage display libraries.

In other preferred methods one or more of the marker is measured usinglaser desorption/ionization mass spectrometry, comprising providing aprobe adapted for use with a mass spectrometer comprising an adsorbentattached thereto, and contacting the subject sample with the adsorbent,and; desorbing and ionizing the marker from the probe and detecting thedeionized/ionized markers with the mass spectrometer.

Preferably, the laser desorption/ionization mass spectrometry comprises:providing a substrate comprising an adsorbent attached thereto;contacting the subject sample with the adsorbent; placing the substrateon a probe adapted for use with a mass spectrometer comprising anadsorbent attached thereto; and, desorbing and ionizing the marker fromthe probe and detecting the desorbed/ionized marker with the massspectrometer. The adsorbent can for example be hydrophobic, hydrophilic,ionic or metal chelate adsorbent, such as, nickel or an antibody,single- or double stranded oligonucleotide, amino acid, protein, peptideor fragments thereof.

The methods of the present invention can be performed on any type ofpatient sample that would be amenable to such methods, e.g., blood,serum and plasma.

The present invention also provides kits comprising (a) a capturereagent that binds the CTAP3-related biomarker; and (b) a containercomprising the biomarker. In preferred embodiments, the capture reagentbinds the biomarker. While the capture reagent can be any type ofreagent, preferably the reagent is a SELDI probe. The capture reagentmay also bind other known biomarkersas disclosed herein. In certainpreferred embodiments, the kit of further comprises a second capturereagent that binds the biomarker that the first capture reagent did notbind.

In certain kits of the present invention, the capture reagent comprisesan immobilized metal chelate (“IMAC”).

Certain kits of the present invention further comprise a wash solutionthat selectively allows retention of the bound biomarker to the capturereagent as compared with other biomarkers after washing.

The invention also provides kits comprising (a) a first capture reagentthat binds the CTAP3-related biomarker, and (b) instructions for usingthe capture reagent to measure the biomarker. In certain of these kits,the capture reagent comprises an antibody. Furthermore, some kitsfurther comprise an MS probe to which the capture reagent is attached oris attachable. In some kits, the capture reagent comprises an IMAC. Thekits may also contain a wash solution that selectively allows retentionof the bound biomarker to the capture reagent as compared with otherbiomarkers after washing. Preferably, the kit comprises writteninstructions for use of the kit for determining ovarian cancer statusand the instructions provide for contacting a test sample with thecapture reagent and measuring one or more biomarkers retained by thecapture reagent.

The kit also provides for a capture reagent, which is an antibody,single or double stranded oligonucleotide, amino acid, protein, peptideor fragments thereof. Measurement of the protein biomarker using thekit, is by mass spectrometry or immunoassays such as an ELISA.

Purified proteins for detection of ovarian cancer and/or generation ofantibodies for further diagnostic assays are also provided for. Purifiedproteins include, for example, a purified peptide of CTAP3. Theinvention also provides this purified peptide further comprising adetectable label.

In another embodiment, non-invasive medical imaging techniques such astransvaginal ultrasound, positron emission tomography (PET) or singlephoton emission computerized tomography (SPECT) imaging are particularlyuseful for the detection of cancer, coronary artery disease and braindisease. Ultrasound with Doppler flow, PET, and SPECT imaging show thechemical functioning of organs and tissues, while other imagingtechniques such as X-ray, CT and MRI primarily show structure. The useof ultrasound with flow, PET and SPECT imaging has become increasinglyuseful for qualifying and monitoring the development of diseases such asovarian cancer.

The CTAP3-related biomarkers disclosed herein, or fragments thereof, canbe used in the context of PET and SPECT imaging applications. Aftermodification with appropriate tracer residues for PET or SPECTapplications, the CTAP3-related biomarker that interacts with tumorproteins can be used to image the deposition of biomarkers in ovariancancer patients.

Other aspects of the invention are described infra.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 (includes F1A through 1E) shows mass spectra of the CTAP3 marker.The mass spectral peak of the marker is designated within the depictedspectra with a vertical line.

FIG. 2 represents the amino acid sequence of precursor platelet basicprotein (PPBP) (Swiss Prot Accession No.: P02775) (SEQ ID NO: 1). CTAP3is an 85 amino acid protein comprising amino acid residues 44-128 ofPPBP.

DETAILED DESCRIPTION OF THE INVENTION 1. Introduction

A biomarker is an organic biomolecule which is differentially present ina sample taken from a subject of one phenotypic status (e.g., having adisease) as compared with another phenotypic status (e.g., not havingthe disease). A biomarker is differentially present between differentphenotypic statuses if the mean or median expression level of thebiomarker in the different groups is calculated to be statisticallysignificant. Common tests for statistical significance include, amongothers, t-test, ANOVA, Kruskal-Wallis, Wilcoxon, Mann-Whitney and oddsratio. Biomarkers, alone or in combination, provide measures of relativerisk that a subject belongs to one phenotypic status or another.Therefore, they are useful as markers for disease (diagnostics),therapeutic effectiveness of a drug (theranostics) and drug toxicity.

2. Biomarkers for Ovarian Cancer 2.1. Biomarkers

This invention provides polypeptide-based biomarkers, CTAP3-relatedproteins (also called “CTAP-III related proteins”), that aredifferentially present in subjects having ovarian cancer, in particular,ovarian cancer versus normal (non-ovarian cancer). The biomarker ischaracterized by mass-to-charge ratio as determined by massspectrometry, by the shape of their spectral peak in time-of-flight massspectrometry and by their binding characteristics to adsorbent surfaces.These characteristics provide one method to determine whether aparticular detected biomolecule is a biomarker of this invention. Thesecharacteristics represent inherent characteristics of the biomoleculesand not process limitations in the manner in which the biomolecules arediscriminated. In one aspect, this invention provides this biomarker inisolated form.

The biomarker was discovered using SELDI technology employingProteinChip arrays from Ciphergen Biosystems, Inc. (Fremont, Calif.)(“Ciphergen”). Serum samples were collected from subjects diagnosed withovarian cancer and subjects diagnosed as normal. The samples werefractionated by anion exchange chromatography. Fractionated samples wereapplied to SELDI biochips and spectra of polypeptides in the sampleswere generated by time-of-flight mass spectrometry on a Ciphergen PCS4000 mass spectrometer. The spectra thus obtained were analyzed byCiphergen Express™ Data Manager Software with Biomarker Wizard andBiomarker Pattern Software from Ciphergen Biosystems, Inc. The massspectra for each group were subjected to scatter plot analysis. AMann-Whitney test analysis was employed to compare ovarian cancer andcontrol groups for each protein cluster in the scatter plot, andproteins were selected that differed significantly (p<0.0001) betweenthe two groups. This method is described in more detail in the ExampleSection.

The invention provides biomarkers referred to herein as CTAP3-relatedproteins or CTAP3-related biomarkers. The CTAP3-related biomarkersinclude peptides and polypeptides that comprise amino acid sequencesderived from precursor platelet basic protein (PPBP) (SEQ ID NO:1),including fragments thereof.

In specific embodiments, the invention provides the CTAP3 biomarker.CTAP3 is an 85 amino acid protein derived from PPBP (SwissProt P02775).CTAP3 is recognized by antibodies available from, e.g., ChemiconInternational (catalog 1484P) (www.chemicon.com, Temecula, Calif.).CTAP3 is a fragment of precursor platelet basic protein and consistingof amino acids 44-128 of SEQ ID NO:1.

The “ProteinChip assay” column refers to chromatographic fraction inwhich the biomarker is found, the type of biochip to which the biomarkerbinds and the wash conditions, as discussed below.

TABLE 1 Up or down regulated in Marker P-Value ovarian cancerProteinChip ® assay CTAP3 <0.0001 Up IMAC-Cu (M9313.9) 100 mM Naphosphate, (predicted mass: pH 7.0 9293)

The biomarker of this invention is characterized by their mass-to-chargeratio as determined by mass spectrometry. The mass-to-charge ratio ofthe biomarker is provided in Table 1 after the “M.” Thus, for example,CTAP has a measured mass-to-charge ratio of 9313.9. The mass-to-chargeratios were determined from mass spectra generated on a CiphergenBiosystems, Inc. PBS II mass spectrometer. This instrument has a massaccuracy of about +/−0.15 percent. Additionally, the instrument has amass resolution of about 400 to 1000 m/dm, where m is mass and dm is themass spectral peak width at 0.5 peak height. The mass-to-charge ratio ofthe biomarkers was determined using Biomarker Wizard™ software(Ciphergen Biosystems, Inc.). Biomarker Wizard assigns a mass-to-chargeratio to a biomarker by clustering the mass-to-charge ratios of the samepeaks from all the spectra analyzed, as determined by the PBSII, takingthe maximum and minimum mass-to-charge-ratio in the cluster, anddividing by two. Accordingly, the masses provided reflect thesespecifications.

The biomarker of this invention can be further characterized by theshape and/or location of its mass spectral speak(s). Mass spectrashowing peaks representing the biomarker are presented in FIG. 1. Inthat FIG. 1, the spectra (FIGS. 1A through 1E) were generated throughSELDI analysis and show mass values differing than the values set forthin Table 1. Those differing mass values are attributed to differences ininternal calibration of the analysis tools.

The biomarker of this invention is further characterized by its bindingproperties on chromatographic surfaces. CTAP3 binds to IMAC-Cu afterwashing with sodium phosphate, pH 7.

The identity of a biomarker of this invention has been determined and isindicated in Table 1. The method by which this determination was made isdescribed in the Example section below.

The preferred biological source for detection of the biomarkers isserum. However, in other embodiments, the biomarkers can be detected inplasma or urine.

The biomarker of this invention is a polypeptide. Accordingly, thisinvention provides this polypeptide in isolated form. The biomarker canbe isolated from biological fluids, such as urine or serum. It can beisolated by any method known in the art, based on both their mass andtheir binding characteristics. For example, a sample comprising thepolypeptide can be subject to chromatographic fractionation, asdescribed herein, and subject to further separation by, e.g., acrylamidegel electrophoresis. Knowledge of the identity of the biomarker alsoallows their isolation by immunoaffinity chromatography.

A biomarker of this invention, CTAP3, has been demonstrated todifferentially present in several classes. It was found in a comparisonof samples from early stage ovarian cancer versus healthy controls;early stage ovarian cancer versus post-operative cancer free (serialsamples from patients before and after treatment), and early stageovarian cancer versus benign disease, either ovarian or non-ovariandisease.

3. Biomarkers and Different Forms of a Protein

Proteins frequently exist in a sample in a plurality of different forms.These forms can result from either or both of pre- andpost-translational modification. Pre-translational modified formsinclude allelic variants, splice variants and RNA editing forms.Post-translationally modified forms include forms resulting fromproteolytic cleavage (e.g., cleavage of a signal sequence or fragmentsof a parent protein), glycosylation, phosphorylation, lipidation,oxidation, methylation, cysteinylation, sulphonation and acetylation.

Accordingly, the invention provides biomarkers referred to herein as“CTAP3-related proteins” or “CTAP3-related biomarkers”. TheCTAP3-related biomarkers include peptides and proteins that compriseamino acid sequences derived from precursor platelet basic protein(PPBP), including fragments thereof. Exemplary CTAP3-related biomarkersinclude polypeptides referred to in the literature as B TG1, Beta TG,Beta thromboglobulin, Chemokine (C X C motif) ligand 7, Connectivetissue activating peptide III, CXC chemokine ligand 7, CXCL7, LA PF4,LDGF, Low affinity platelet factor IV, MDGF, NAP 2 L1, Neutrophilactivating peptide 2, PBP, Platelet basic protein precursor, Proplatelet basic protein, SCYB7, Small inducible cytokine B7, Smallinducible cytokine subfamily B member 7, TC1, TC2, TGB, TGB1, THBGB,THBGB1, Thrombocidin 1, Thrombocidin 2, and Thromboglobulin beta 1.Table 2 sets forth exemplary CTAP3-related molecules and the amino acidresidues of PPBP that each molecule contains.

TABLE 2 Exemplary CTAP3-related molecules Amino Acid Residues of PBPPPeptide Name (SEQ ID NO: 1) Macrophage-derived growth factor (MDGF) 1-128 Small inducible cytokine B7 (CXCL7)  1-128 Leukocyte-derivedgrowth factor (LDGF)  1-128 Platelet basic protein (Mature form) 35-128Connective tissue-activating peptide III 44-128 (CTAP3) Connectivetissue-activating peptide 3a 44-124 (CTAP3a) TC-2 44-126Beta-thromboglobulin 48-128 TC-1 59-126 Neutrophil-activating peptide 255-128 Neutrophil-activating peptide 2 59-124 Neutrophil-activatingpeptide 2 59-121 Low-affinity platelet factor IV (LA-PF4) 59-128Chemokine_CXC 60-122

When detecting or measuring a protein in a sample, the ability todifferentiate between different forms of a protein depends upon thenature of the difference and the method used to detect or measure. Forexample, an immunoassay using a monoclonal antibody will detect allforms of a protein containing the eptiope and will not distinguishbetween them. However, a sandwich immunoassay that uses two antibodiesdirected against different epitopes on a protein will detect all formsof the protein that contain both epitopes and will not detect thoseforms that contain only one of the epitopes. In diagnostic assays, theinability to distinguish different forms of a protein has little impactwhen the forms detected by the particular method used are equally goodbiomarkers as any particular form. However, when a particular form (or asubset of particular forms) of a protein is a better biomarker than thecollection of different forms detected together by a particular method,the power of the assay may suffer. In this case, it is useful to employan assay method that distinguishes between forms of a protein and thatspecifically detects and measures a desired form or forms of theprotein. Distinguishing different forms of an analyte or specificallydetecting a particular form of an analyte is referred to as “resolving”the analyte.

Mass spectrometry is a particularly powerful methodology to resolvedifferent forms of a protein because the different forms typically havedifferent masses that can be resolved by mass spectrometry. Accordingly,if one form of a protein is a superior biomarker for a disease thananother form of the biomarker, mass spectrometry may be able tospecifically detect and measure the useful form where traditionalimmunoassay fails to distinguish the forms and fails to specificallydetect to useful biomarker.

One useful methodology combines mass spectrometry with immunoassay.First, a biosepcific capture reagent (e.g., an antibody, aptamer orAffibody that recognizes the biomarker and other forms of it) is used tocapture the biomarker of interest. Preferably, the biospecific capturereagent is bound to a solid phase, such as a bead, a plate, a membraneor an array. After unbound materials are washed away, the capturedanalytes are detected and/or measured by mass spectrometry. (This methodalso will also result in the capture of protein interactors that arebound to the proteins or that are otherwise recognized by antibodies andthat, themselves, can be biomarkers.) Various forms of mass spectrometryare useful for dectecting the protein forms, including laser desorptionapproaches, such as traditional MALDI or SELDI, and electrosprayionization.

Thus, when reference is made herein to detecting a particular protein orto measuring the amount of a particular protein, it means detecting andmeasuring the protein with or without resolving various forms ofprotein. For example, the step of “measuring CTAP3” includes measuringCTAP3 by means that do not differentiate between various forms of theprotein (e.g., certain immunoassays) as well as by means thatdifferentiate some forms from other forms or that measure a specificform of the protein. In contrast, when it is desired to measure aparticular form or forms of a protein, e.g., a particular form of CTAP3,the particular form (or forms) is specified. For example, “measuringM9313.9” means measuring CTAP3 in a way that distinguishes M9313.9 fromother forms of CTAP3.

4. Detection of Biomarkers for Ovarian Cancer

The biomarkers of this invention can be detected by any suitable method.Detection paradigms that can be employed to this end include opticalmethods, electrochemical methods (voltametry and amperometrytechniques), atomic force microscopy, and radio frequency methods, e.g.,multipolar resonance spectroscopy. Illustrative of optical methods, inaddition to microscopy, both confocal and non-confocal, are detection offluorescence, luminescence, chemiluminescence, absorbance, reflectance,transmittance, and birefringence or refractive index (e.g., surfaceplasmon resonance, ellipsometry, a resonant mirror method, a gratingcoupler waveguide method or interferometry).

In one embodiment, a sample is analyzed by means of a biochip. Biochipsgenerally comprise solid substrates and have a generally planar surface,to which a capture reagent (also called an adsorbent or affinityreagent) is attached. Frequently, the surface of a biochip comprises aplurality of addressable locations, each of which has the capturereagent bound there.

Protein biochips are biochips adapted for the capture of polypeptides.Many protein biochips are described in the art. These include, forexample, protein biochips produced by Ciphergen Biosystems, Inc.(Fremont, Calif.), Zyomyx (Hayward, Calif.), Invitrogen (Carlsbad,Calif.), Biacore (Uppsala, Sweden) and Procognia (Berkshire, UK).Examples of such protein biochips are described in the following patentsor published patent applications: U.S. Pat. No. 6,225,047 (Hutchens &Yip); U.S. Pat. No. 6,537,749 (Kuimelis and Wagner); U.S. Pat. No.6,329,209 (Wagner et al.); PCT International Publication No. WO 00/56934(Englert et al.); PCT International Publication No. WO 03/048768(Boutell et al.) and U.S. Pat. No. 5,242,828 (Bergstrom et al.).

4.1. Detection by Mass Spectrometry

In a preferred embodiment, the biomarkers of this invention are detectedby mass spectrometry, a method that employs a mass spectrometer todetect gas phase ions. Examples of mass spectrometers aretime-of-flight, magnetic sector, quadrupole filter, ion trap, ioncyclotron resonance, electrostatic sector analyzer and hybrids of these.

In a further preferred method, the mass spectrometer is a laserdesorption/ionization mass spectrometer. In laser desorption/ionizationmass spectrometry, the analytes are placed on the surface of a massspectrometry probe, a device adapted to engage a probe interface of themass spectrometer and to present an analyte to ionizing energy forionization and introduction into a mass spectrometer. A laser desorptionmass spectrometer employs laser energy, typically from an ultravioletlaser, but also from an infrared laser, to desorb analytes from asurface, to volatilize and ionize them and make them available to theion optics of the mass spectrometer. The analysis of proteins by LDI cantake the form of MALDI or of SELDI. The analysis of proteins by LDI cantake the form of MALDI or of SELDI.

Laser desorption/ionization in a single TOF instrument typically isperformed in linear extraction mode. Tandem mass spectrometers canemploy orthogonal extraction modes.

4.1.1. SELDI

A preferred mass spectrometric technique for use in the invention is“Surface Enhanced Laser Desorption and Ionization” or “SELDI,” asdescribed, for example, in U.S. Pat. No. 5,719,060 and No. 6,225,047,both to Hutchens and Yip. This refers to a method ofdesorption/ionization gas phase ion spectrometry (e.g., massspectrometry) in which an analyte (here, one or more of the biomarkers)is captured on the surface of a SELDI mass spectrometry probe.

SELDI also has been called is called “affinity capture massspectrometry” or “Surface-Enhanced Affinity Capture” (“SEAC”). Thisversion involves the use of probes that have a material on the probesurface that captures analytes through a non-covalent affinityinteraction (adsorption) between the material and the analyte. Thematerial is variously called an “adsorbent,” a “capture reagent,” an“affinity reagent” or a “binding moiety.” Such probes can be referred toas “affinity capture probes” and as having an “adsorbent surface.” Thecapture reagent can be any material capable of binding an analyte. Thecapture reagent is attached to the probe surface by physisorption orchemisorption. In certain embodiments the probes have the capturereagent already attached to the surface. In other embodiments, theprobes are pre-activated and include a reactive moiety that is capableof binding the capture reagent, e.g., through a reaction forming acovalent or coordinate covalent bond. Epoxide and acyl-imidizole areuseful reactive moieties to covalently bind polypeptide capture reagentssuch as antibodies or cellular receptors. Nitrilotriacetic acid andiminodiacetic acid are useful reactive moieties that function aschelating agents to bind metal ions that interact non-covalently withhistidine containing peptides. Adsorbents are generally classified aschromatographic adsorbents and biospecific adsorbents.

“Chromatographic adsorbent” refers to an adsorbent material typicallyused in chromatography. Chromatographic adsorbents include, for example,ion exchange materials, metal chelators (e.g., nitrilotriacetic acid oriminodiacetic acid), immobilized metal chelates, hydrophobic interactionadsorbents, hydrophilic interaction adsorbents, dyes, simplebiomolecules (e.g., nucleotides, amino acids, simple sugars and fattyacids) and mixed mode adsorbents (e.g., hydrophobicattraction/electrostatic repulsion adsorbents).

“Biospecific adsorbent” refers to an adsorbent comprising a biomolecule,e.g., a nucleic acid molecule (e.g., an aptamer), a polypeptide, apolysaccharide, a lipid, a steroid or a conjugate of these (e.g., aglycoprotein, a lipoprotein, a glycolipid, a nucleic acid (e.g.,DNA)-protein conjugate). In certain instances, the biospecific adsorbentcan be a macromolecular structure such as a multiprotein complex, abiological membrane or a virus. Examples of biospecific adsorbents areantibodies, receptor proteins and nucleic acids. Biospecific adsorbentstypically have higher specificity for a target analyte thanchromatographic adsorbents. Further examples of adsorbents for use inSELDI can be found in U.S. Pat. No. 6,225,047. A “bioselectiveadsorbent” refers to an adsorbent that binds to an analyte with anaffinity of at least 10⁻⁸ M.

Protein biochips produced by Ciphergen comprise surfaces havingchromatographic or biospecific adsorbents attached thereto ataddressable locations. Ciphergen's ProteinChip® arrays include NP20(hydrophilic); H4 and H50 (hydrophobic); SAX-2, Q-10 and (anionexchange); WCX-2 and CM-10 (cation exchange); IMAC-3, IMAC-30 andIMAC-50 (metal chelate); and PS-10, PS-20 (reactive surface withacyl-imidizole, epoxide) and PG-20 (protein G coupled throughacyl-imidizole). Hydrophobic ProteinChip arrays have isopropyl ornonylphenoxy-poly(ethylene glycol)methacrylate functionalities. Anionexchange ProteinChip arrays have quaternary ammonium functionalities.Cation exchange ProteinChip arrays have carboxylate functionalities.Immobilized metal chelate ProteinChip arrays have nitrilotriacetic acidfunctionalities (IMAC 3 and IMAC 30) orO-methacryloyl-N,N-bis-carboxymethyl tyrosine funtionalities (IMAC 50)that adsorb transition metal ions, such as copper, nickel, zinc, andgallium, by chelation. Preactivated ProteinChip arrays haveacyl-imidizole or epoxide functional groups that can react with groupson proteins for covalent binding.

Such bio chips are further described in: U.S. Pat. No. 6,579,719(Hutchens and Yip, “Retentate Chromatography,” Jun. 17, 2003); U.S. Pat.No. 6,897,072 (Rich et al., “Probes for a Gas Phase Ion Spectrometer,”May 24, 2005); U.S. Pat. No. 6,555,813 (Beecher et al., “Sample Holderwith Hydrophobic Coating for Gas Phase Mass Spectrometer,” Apr. 29,2003); U.S. Patent Publication No. U.S. 2003-0032043 A1 (Pohl andPapanu, “Latex Based Adsorbent Chip,” Jul. 16, 2002); and PCTInternational Publication No. WO 03/040700 (Um et al., “HydrophobicSurface Chip,” May 15, 2003); U.S. Patent Publication No. US2003-0218130 A1 (Boschetti et al., “Biochips With Surfaces Coated WithPolysaccharide-Based Hydrogels,” Apr. 14, 2003) and U.S. Pat. No.7,045,366 (Huang et al., “Photocrosslinked Hydrogel Blend SurfaceCoatings,” May 16, 2006).

In general, a probe with an adsorbent surface is contacted with thesample for a period of time sufficient to allow the biomarker orbiomarkers that may be present in the sample to bind to the adsorbent.After an incubation period, the substrate is washed to remove unboundmaterial. Any suitable washing solutions can be used; preferably,aqueous solutions are employed. The extent to which molecules remainbound can be manipulated by adjusting the stringency of the wash. Theelution characteristics of a wash solution can depend, for example, onpH, ionic strength, hydrophobicity, degree of chaotropism, detergentstrength, and temperature. Unless the probe has both SEAC and SENDproperties (as described herein), an energy absorbing molecule then isapplied to the substrate with the bound biomarkers.

In yet another method, one can capture the biomarkers with a solid-phasebound immuno-adsorbent that has antibodies that bind the biomarkers.After washing the adsorbent to remove unbound material, the biomarkersare eluted from the solid phase and detected by applying to a SELDIbiochip that binds the biomarkers and analyzing by SELDI.

The biomarkers bound to the substrates are detected in a gas phase ionspectrometer such as a time-of-flight mass spectrometer. The biomarkersare ionized by an ionization source such as a laser, the generated ionsare collected by an ion optic assembly, and then a mass analyzerdisperses and analyzes the passing ions. The detector then translatesinformation of the detected ions into mass-to-charge ratios. Detectionof a biomarker typically will involve detection of signal intensity.Thus, both the quantity and mass of the biomarker can be determined.

4.1.2. SEND

Another method of laser desorption mass spectrometry is calledSurface-Enhanced Neat Desorption (“SEND”). SEND involves the use ofprobes comprising energy absorbing molecules that are chemically boundto the probe surface (“SEND probe”). The phrase “energy absorbingmolecules” (EAM) denotes molecules that are capable of absorbing energyfrom a laser desorption/ionization source and, thereafter, contribute todesorption and ionization of analyte molecules in contact therewith. TheEAM category includes molecules used in MALDI, frequently referred to as“matrix,” and is exemplified by cinnamic acid derivatives, sinapinicacid (SPA), cyano-hydroxy-cinnamic acid (CHCA) and dihydroxybenzoicacid, ferulic acid, and hydroxyaceto-phenone derivatives. In certainembodiments, the energy absorbing molecule is incorporated into a linearor cross-linked polymer, e.g., a polymethacrylate. For example, thecomposition can be a co-polymer of α-cyano-4-methacryloyloxycinnamicacid and acrylate. In another embodiment, the composition is aco-polymer of α-cyano-4-methacryloyloxycinnamic acid, acrylate and3-(tri-ethoxy)silyl propyl methacrylate. In another embodiment, thecomposition is a co-polymer of α-cyano-4-methacryloyloxycinnamic acidand octadecylmethacrylate (“C18 SEND”). SEND is further described inU.S. Pat. No. 6,124,137 and PCT International Publication No. WO03/64594 (Kitagawa, “Monomers And Polymers Having Energy AbsorbingMoieties Of Use In Desorption/Ionization Of Analytes,” Aug. 7, 2003).

SEAC/SEND is a version of laser desorption mass spectrometry in whichboth a capture reagent and an energy absorbing molecule are attached tothe sample presenting surface. SEAC/SEND probes therefore allow thecapture of analytes through affinity capture and ionization/desorptionwithout the need to apply external matrix. The C18 SEND biochip is aversion of SEAC/SEND, comprising a C18 moiety which functions as acapture reagent, and a CHCA moiety which functions as an energyabsorbing moiety.

4.1.3. SEPAR

Another version of LDI is called Surface-Enhanced Photolabile Attachmentand Release (“SEPAR”). SEPAR involves the use of probes having moietiesattached to the surface that can covalently bind an analyte, and thenrelease the analyte through breaking a photolabile bond in the moietyafter exposure to light, e.g., to laser light (see, U.S. Pat. No.5,719,060). SEPAR and other forms of SELDI are readily adapted todetecting a biomarker or biomarker profile, pursuant to the presentinvention.

4.1.4. MALDI

MALDI is a traditional method of laser desorption/ionization used toanalyte biomolecules such as proteins and nucleic acids. In one MALDImethod, the sample is mixed with matrix and deposited directly on aMALDI array. However, the complexity of biological samples such as serumand urine makes this method less than optimal without priorfractionation of the sample. Accordingly, in certain embodiments withbiomarkers are preferably first captured with biospecific (e.g., anantibody) or chromatographic materials coupled to a solid support suchas a resin (e.g., in a spin column). Specific affinity materials thatbind the biomarkers of this invention are described above. Afterpurification on the affinity material, the biomarkers are eluted andthen detected by MALDI.

In another mass spectrometry method, the biomarkers can be firstcaptured on a chromatographic resin having chromatographic propertiesthat bind the biomarkers. In the present example, this could include avariety of methods. For example, one could capture the biomarkers on acation exchange resin, such as CM Ceramic HyperD F resin, wash theresin, elute the biomarkers and detect by MALDI. Alternatively, thismethod could be preceded by fractionating the sample on an anionexchange resin before application to the cation exchange resin. Inanother alternative, one could fractionate on an anion exchange resinand detect by MALDI directly. In yet another method, one could capturethe biomarkers on an immuno-chromatographic resin that comprisesantibodies that bind the biomarkers, wash the resin to remove unboundmaterial, elute the biomarkers from the resin and detect the elutedbiomarkers by MALDI or by SELDI.

4.1.5. Other Forms of Ionization in Mass Spectrometry

In another method, the biomarkers are detected by LC-MS or LC-LC-MS.This involves resolving the proteins in a sample by one or two passesthrough liquid chromatography, followed by mass spectrometry analysis,typically electrospray ionization.

4.1.6. Data Analysis

Analysis of analytes by time-of-flight mass spectrometry generates atime-of-flight spectrum. The time-of-flight spectrum ultimately analyzedtypically does not represent the signal from a single pulse of ionizingenergy against a sample, but rather the sum of signals from a number ofpulses. This reduces noise and increases dynamic range. Thistime-of-flight data is then subject to data processing. In Ciphergen'sProteinChip® software, data processing typically includes TOF-to-M/Ztransformation to generate a mass spectrum, baseline subtraction toeliminate instrument offsets and high frequency noise filtering toreduce high frequency noise.

Data generated by desorption and detection of biomarkers can be analyzedwith the use of a programmable digital computer. The computer programanalyzes the data to indicate the number of biomarkers detected, andoptionally the strength of the signal and the determined molecular massfor each biomarker detected. Data analysis can include steps ofdetermining signal strength of a biomarker and removing data deviatingfrom a predetermined statistical distribution. For example, the observedpeaks can be normalized, by calculating the height of each peak relativeto some reference.

The computer can transform the resulting data into various formats fordisplay. The standard spectrum can be displayed, but in one usefulformat only the peak height and mass information are retained from thespectrum view, yielding a cleaner image and enabling biomarkers withnearly identical molecular weights to be more easily seen. In anotheruseful format, two or more spectra are compared, convenientlyhighlighting unique biomarkers and biomarkers that are up- ordown-regulated between samples. Using any of these formats, one canreadily determine whether a particular biomarker is present in a sample.

Analysis generally involves the identification of peaks in the spectrumthat represent signal from an analyte. Peak selection can be donevisually, but software is available, as part of Ciphergen's ProteinChip®software package, that can automate the detection of peaks. In general,this software functions by identifying signals having a signal-to-noiseratio above a selected threshold and labeling the mass of the peak atthe centroid of the peak signal. In one useful application, many spectraare compared to identify identical peaks present in some selectedpercentage of the mass spectra. One version of this software clustersall peaks appearing in the various spectra within a defined mass range,and assigns a mass (M/Z) to all the peaks that are near the mid-point ofthe mass (M/Z) cluster.

Software used to analyze the data can include code that applies analgorithm to the analysis of the signal to determine whether the signalrepresents a peak in a signal that corresponds to a biomarker accordingto the present invention. The software also can subject the dataregarding observed biomarker peaks to classification tree or ANNanalysis, to determine whether a biomarker peak or combination ofbiomarker peaks is present that indicates the status of the particularclinical parameter under examination. Analysis of the data may be“keyed” to a variety of parameters that are obtained, either directly orindirectly, from the mass spectrometric analysis of the sample. Theseparameters include, but are not limited to, the presence or absence ofone or more peaks, the shape of a peak or group of peaks, the height ofone or more peaks, the log of the height of one or more peaks, and otherarithmetic manipulations of peak height data.

4.1.7. General Protocol for SELDI Detection of Biomarkers for OvarianCancer

A preferred protocol for the detection of the biomarker of thisinvention is as follows. The biological sample to be tested, e.g.,serum, preferably is subject to pre-fractionation before SELDI analysis.This simplifies the sample and improves sensitivity. A preferred methodof pre-fractionation involves contacting the sample with an anionexchange chromatographic material, such as Q HyperD (BioSepra, SA). Thebound materials are then subject to stepwise pH elution using buffers atpH 9, pH 7, pH 5, pH 4, pH 3 and organic wash. Various fractionscontaining the biomarker are collected. CTAP3 is found in organic washfraction and also can be found in the pH 4 fraction.

The sample to be tested (preferably pre-fractionated) is then contactedwith an affinity capture probe comprising an IMAC-Cu biochip. The probeis washed with a buffer that will retain the biomarker while washingaway unbound molecules. A suitable wash for each biomarker is the bufferidentified in Table 1. The biomarkers are detected by laserdesorption/ionization mass spectrometry.

Alternatively, if antibodies that recognize CTAP3 the biomarker areavailable, these can be attached to the surface of a probe, such as apre-activated PS10 or PS20 ProteinChip array (Ciphergen Biosystems,Inc.). These antibodies can capture the biomarkers from a sample ontothe probe surface. Then the biomarkers can be detected by, e.g., laserdesorption/ionization mass spectrometry.

4.2. Detection by Immunoassay

In another embodiment of the invention, the biomarkers of the inventionare measured by a method other than mass spectrometry or other thanmethods that rely on a measurement of the mass of the biomarker. In onesuch embodiment that does not rely on mass, the biomarkers of thisinvention are measured by immunoassay. Immunoassay requires biospecificcapture reagents, such as antibodies, to capture the biomarkers.Antibodies can be produced by methods well known in the art, e.g., byimmunizing animals with the biomarkers. Biomarkers can be isolated fromsamples based on their binding characteristics. Alternatively, if theamino acid sequence of a polypeptide biomarker is known, the polypeptidecan be synthesized and used to generate antibodies by methods well knownin the art.

This invention contemplates traditional immunoassays including, forexample, sandwich immunoassays including ELISA or fluorescence-basedimmunoassays, as well as other enzyme immunoassays. Nephelometry is anassay done in liquid phase, in which antibodies are in solution. Bindingof the antigen to the antibody results in changes in absorbance, whichis measured. In the SELDI-based immunoassay, a bio specific capturereagent for the biomarker is attached to the surface of an MS probe,such as a pre-activated ProteinChip array. The biomarker is thenspecifically captured on the biochip through this reagent, and thecaptured biomarker is detected by mass spectrometry.

5. Determination of Subject Ovarian Cancer Status

The biomarkers of the invention can be used in diagnostic tests toassess ovarian cancer status in a subject, e.g., to diagnose ovariancancer. The phrase “ovarian cancer status” includes any distinguishablemanifestation of the disease, including non-disease. For example,ovarian cancer status includes, without limitation, the presence orabsence of disease (e.g., ovarian cancer v. non-ovarian cancer), therisk of developing disease, the stage of the disease, the progression ofdisease (e.g., progress of disease or remission of disease over time)and the effectiveness or response to treatment of disease.

The correlation of test results with ovarian cancer status involvesapplying a classification algorithm of some kind to the results togenerate the status. The classification algorithm may be as simple asdetermining whether or not the amount of a CTAP3-related protein, e.g.,CTAP3, measured is above or below a particular cut-off number. Whenmultiple biomarkers are used, the classification algorithm may be alinear regression formula. Alternatively, the classification algorithmmay be the product of any of a number of learning algorithms describedherein.

In the case of complex classification algorithms, it may be necessary toperform the algorithm on the data, thereby determining theclassification, using a computer, e.g., a programmable digital computer.In either case, one can then record the status on tangible medium, forexample, in computer-readable format such as a memory drive or disk orsimply printed on paper. The result also could be reported on a computerscreen.

5.1. Single Markers

The biomarker of the invention can be used in diagnostic tests to assessovarian cancer status in a subject, e.g., to diagnose ovarian cancer.The phrase “ovarian cancer status” includes any distinguishablemanifestation of the disease, including non-disease. For example,disease status includes, without limitation, the presence or absence ofdisease (e.g., ovarian cancer v. non-ovarian cancer), the risk ofdeveloping disease, the stage of the disease, the progress of disease(e.g., progress of disease or remission of disease over time) and theeffectiveness or response to treatment of disease. Based on this status,further procedures may be indicated, including additional diagnostictests or therapeutic procedures or regimens.

The power of a diagnostic test to correctly predict status is commonlymeasured as the sensitivity of the assay, the specificity of the assayor the area under a receiver operated characteristic (“ROC”) curve.Sensitivity is the percentage of true positives that are predicted by atest to be positive, while specificity is the percentage of truenegatives that are predicted by a test to be negative. An ROC curveprovides the sensitivity of a test as a function of 1-specificity. Thegreater the area under the ROC curve, the more powerful the predictivevalue of the test. Other useful measures of the utility of a test arepositive predictive value and negative predictive value. Positivepredictive value is the percentage of people who test positive that areactually positive. Negative predictive value is the percentage of peoplewho test negative that are actually negative.

The biomarkers of this invention show a statistical difference indifferent ovarian cancer statuses of at least p≦0.05, p≦10⁻², p≦10⁻³,p≦10⁻⁴ or p≦10⁻⁵. Diagnostic tests that use these biomarkers alone or incombination show a sensitivity and specificity of at least 75%, at least80%, at least 85%, at least 90%, at least 95%, at least 98% and about100%.

CTAP3 is differentially present in ovarian cancer, and, therefore, eachis individually useful in aiding in the determination of ovarian cancerstatus. The method involves, first, measuring the selected biomarker ina subject sample using the methods described herein, e.g., capture on aSELDI biochip followed by detection by mass spectrometry and, second,comparing the measurement with a diagnostic amount or cut-off thatdistinguishes a positive ovarian cancer status from a negative ovariancancer status. The diagnostic amount represents a measured amount of abiomarker above which or below which a subject is classified as having aparticular ovarian cancer status. For example, if the biomarker isup-regulated compared to normal during ovarian cancer, then a measuredamount above the diagnostic cutoff provides a diagnosis of ovariancancer. Alternatively, if the biomarker is down-regulated during ovariancancer, then a measured amount below the diagnostic cutoff provides adiagnosis of ovarian cancer. As is well understood in the art, byadjusting the particular diagnostic cut-off used in an assay, one canincrease sensitivity or specificity of the diagnostic assay depending onthe preference of the diagnostician. The particular diagnostic cut-offcan be determined, for example, by measuring the amount of the biomarkerin a statistically significant number of samples from subjects with thedifferent ovarian cancer statuses, as was done here, and drawing thecut-off to suit the diagnostician's desired levels of specificity andsensitivity.

5.2. Combinations of Markers

While individual biomarkers are useful diagnostic biomarkers, it hasbeen found that a combination of biomarkers can provide greaterpredictive value of a particular status than a single biomarker alone.Specifically, the detection of a plurality of biomarkers in a sample canincrease the sensitivity and/or specificity of the test. A combinationof at least two biomarkers, preferably at least three or more than threebiomarkers, is sometimes referred to as a “biomarker profile” or“biomarker fingerprint.” Accordingly, a CTAP3-related protein, e.g.,CTAP3, can be combined with other biomarkers for ovarian or endometrialcancer to improve the sensitivity and/or specificity of the diagnostictest.

In particular, a diagnostic test for ovarian cancer status involving themeasurement of CTAP3 and any of the following biomarkers for ovariancancer identified in Table 3 (including their modified forms whereappropriate) can have greater predictive power than the measurement of aCTAP3-related protein, e.g., CTAP3, alone:

TABLE 3 Marker Comments (up- or down-regulated in cancer) TransferrinDown-regulated; 79 kD, detected on IMAC ProteinChip array charged withnickel WO 03/057014 Haptoglobin precursor Up-regulated; 9.2 kD detectedon IMAC protein fragment ProteinChip array charged with nickel WO03/057014 ApoA1 Down-regulated; predicted mass 28078.62D; detected onIMAC or H50 ProteinChip array. WO 2004/013609 Transthyretin andDown-regulated; predicted mass 13761D and transthyretin delta 12887 D,respectively; detected on Q10 N 10 ProteinChip array. WO 2004/013609ITIH4 internal Up-regulated; among other fragments: fragmentsMNFRPGVLSSRQLGLPGPPDVPDHAAYHPF (SEQ ID NO: 45), a fragment spanningamino acids 660-689 of human Inter-alpha trypsin inhibitor, heavy chainH4, predicted mass: 3273.72 D; detected on IMAC ProteinChip array WO2004/013609 and WO 2005/098447 Beta 2-microglobulin Up-regulated;detected at 11.7 KD on IMAC-Cu ProteinChip array US ProvisionalApplication 60/693,679, filed Jun. 24, 2005 Hepcidin and modifiedUp-regulated; detected by SELDI - co- forms precipitate with ITIH4fragment. Hepcidin-25 (SEQ ID NO: 2): DTHFPICIFCCGCCHRSKCGMCCKTHepcidin-24 (SEQ ID NO: 3): THFPICIFCCGCCHRSKCGMCCKT Hepcidin-22 (SEQ IDNO: 36): FPICIFCCGCCHRSKCGM CCKT Hepcidin-20 (SEQ ID NO: 4):ICIFCCGCCHRSKCGMCCKT Haptoglobin alpha Up-regulated. Detected at11,600D-11,700D on an IMAC ProteinChip array charged with copper; WO02/100242 Prostatin Up-regulated U.S. Pat. No. 6,846,642 OsteopontinUp-regulated In urine - Glycosylated -- US 2005-0009120 A1 In serum - US2005-0214826 Eosinophil-derived Up regulated in urine. GlycosylatedDetected at neurotoxin 17.4 KDa on a WCX2 ProteinChip array. US2005-0009120 A1 leptin Down-regulated; US 2005-0214826 prolactinUp-regulated; US 2005-0214826 IGF-II Down-regulated; US 2005-0214826Hemoglobin Up-regulated; (alpha-hemoglobin, WO 2006-019906beta-hemoglobin) CA 125 Up-regulated

In a study on samples of a Japanese cohort, the combination of hepcidin,ApoA1, β2 microglobulin and CTAP-3 was found to be a particularlyeffective diagnostic combination.

The diagnosis of ovarian cancer typically involves the measurement ofCA125, as increased levels of this marker are correlated with ovariancancer. Therefore, levels of CA125 can be correlated with anycombination of the above markers in determining ovarian cancer status.CA125 is especially useful in that women undergoing tests for ovariancancer typically have CA125 tested as routine part of the work-up.

Other biomarkers with which CTAP3 can be combined include, but are notlimited to, CA125 II, CA15-3, CA19-9, CA72-4, CA 195, tumor associatedtrypsin inhibitor (TATI), CEA, placental alkaline phosphatase (PLAP),Sialyl TN, galactosyltransferase, macrophage colony stimulating factor(M-CSF, CSF-1), lysophosphatidic acid (LPA), 110 kD component of theextracellular domain of the epidermal growth factor receptor (p110EGFR),tissue kallikreins, e.g., kallikrein 6 and kallikrein 10 (NES-1),prostasin, HE4, creatine kinase B (CKB), LASA, HER-2/neu, urinarygonadotropin peptide, Dianon NB 70/K, Tissue peptide antigen (TPA),SMRP, osteopontin, and haptoglobin, leptin, prolactin, insulin likegrowth factor I or II.

5.3. Determining Risk of Developing Disease

In one embodiment, this invention provides methods for determining therisk of developing disease in a subject. Biomarker amounts or patternsare characteristic of various risk states, e.g., high, medium or low.The risk of developing a disease is determined by measuring the relevantbiomarker or biomarkers and then either submitting them to aclassification algorithm or comparing them with a reference amountand/or pattern of biomarkers that is associated with the particular risklevel.

5.4. Determining Stage of Disease

In one embodiment, this invention provides methods for determining thestage of disease in a subject. Each stage of the disease has acharacteristic amount of a biomarker or relative amounts of a set ofbiomarkers (a pattern). The stage of a disease is determined bymeasuring the relevant biomarker or biomarkers and then eithersubmitting them to a classification algorithm or comparing them with areference amount and/or pattern of biomarkers that is associated withthe particular stage.

5.5. Determining Course (Progression/Remission) of Disease

In one embodiment, this invention provides methods for determining thecourse of disease in a subject. Disease course refers to changes indisease status over time, including disease progression (worsening) anddisease regression (improvement). Over time, the amounts or relativeamounts (e.g., the pattern) of the biomarkers changes. For example,CTAP3 is increased with disease. Therefore, the trend of these markers,either increased or decreased over time toward diseased or non-diseasedindicates the course of the disease. Accordingly, this method involvesmeasuring one or more biomarkers in a subject at least two differenttime points, e.g., a first time and a second time, and comparing thechange in amounts, if any. The course of disease is determined based onthese comparisons.

5.6. Reporting the Status

Additional embodiments of the invention relate to the communication ofassay results or diagnoses or both to technicians, physicians orpatients, for example. In certain embodiments, computers will be used tocommunicate assay results or diagnoses or both to interested parties,e.g., physicians and their patients. In some embodiments, the assayswill be performed or the assay results analyzed in a country orjurisdiction which differs from the country or jurisdiction to which theresults or diagnoses are communicated.

In a preferred embodiment of the invention, a diagnosis based on thedifferential presence in a test subject of a CTAP3-related protein iscommunicated to the subject as soon as possible after the diagnosis isobtained. The diagnosis may be communicated to the subject by thesubject's treating physician. Alternatively, the diagnosis may be sentto a test subject by email or communicated to the subject by phone. Acomputer may be used to communicate the diagnosis by email or phone. Incertain embodiments, the message containing results of a diagnostic testmay be generated and delivered automatically to the subject using acombination of computer hardware and software which will be familiar toartisans skilled in telecommunications. One example of ahealthcare-oriented communications system is described in U.S. Pat. No.6,283,761; however, the present invention is not limited to methodswhich utilize this particular communications system. In certainembodiments of the methods of the invention, all or some of the methodsteps, including the assaying of samples, diagnosing of diseases, andcommunicating of assay results or diagnoses, may be carried out indiverse (e.g., foreign) jurisdictions.

5.7. Subject Management

In certain embodiments of the methods of qualifying ovarian cancerstatus, the methods further comprise managing subject treatment based onthe status. Such management includes the actions of the physician orclinician subsequent to determining ovarian cancer status. For example,if a physician makes a diagnosis of ovarian cancer, then a certainregime of treatment, such as prescription or administration oftherapeutic agent, might follow. Alternatively, a diagnosis ofnon-ovarian cancer or non-ovarian cancer might be followed with furthertesting to determine a specific disease that might the patient might besuffering from. Also, if the diagnostic test gives an inconclusiveresult on ovarian cancer status, further tests may be called for.

Additional embodiments of the invention relate to the communication ofassay results or diagnoses or both to technicians, physicians orpatients, for example. In certain embodiments, computers will be used tocommunicate assay results or diagnoses or both to interested parties,e.g., physicians and their patients. In some embodiments, the assayswill be performed or the assay results analyzed in a country orjurisdiction which differs from the country or jurisdiction to which theresults or diagnoses are communicated.

In a preferred embodiment of the invention, a diagnosis based on thepresence or absence in a test subject of the biomarker is communicatedto the subject as soon as possible after the diagnosis is obtained. Thediagnosis may be communicated to the subject by the subject's treatingphysician. Alternatively, the diagnosis may be sent to a test subject byemail or communicated to the subject by phone. A computer may be used tocommunicate the diagnosis by email or phone. In certain embodiments, themessage containing results of a diagnostic test may be generated anddelivered automatically to the subject using a combination of computerhardware and software which will be familiar to artisans skilled intelecommunications. One example of a healthcare-oriented communicationssystem is described in U.S. Pat. No. 6,283,761; however, the presentinvention is not limited to methods which utilize this particularcommunications system. In certain embodiments of the methods of theinvention, all or some of the method steps, including the assaying ofsamples, diagnosing of diseases, and communicating of assay results ordiagnoses, may be carried out in diverse (e.g., foreign) jurisdictions.

5.8. Determining Therapeutic Efficacy of Pharmaceutical Drug

In another embodiment, this invention provides methods for determiningthe therapeutic efficacy of a pharmaceutical drug. These methods areuseful in performing clinical trials of the drug, as well as monitoringthe progress of a patient on the drug. Therapy or clinical trialsinvolve administering the drug in a particular regimen. The regimen mayinvolve a single dose of the drug or multiple doses of the drug overtime. The doctor or clinical researcher monitors the effect of the drugon the patient or subject over the course of administration. If the drughas a pharmacological impact on the condition, the amounts or relativeamounts (e.g., the pattern or profile) of the biomarkers of thisinvention changes toward a non-disease profile. Therefore, one canfollow the course of the amounts of these biomarkers in the subjectduring the course of treatment. Accordingly, this method involvesmeasuring one or more biomarkers in a subject receiving drug therapy,and correlating the amounts of the biomarkers with the disease status ofthe subject. One embodiment of this method involves determining thelevels of the one or more biomarkers at least two different time pointsduring a course of drug therapy, e.g., a first time and a second time,and comparing the change in amounts of the biomarkers, if any. Forexample, the one or more biomarkers can be measured before and afterdrug administration or at two different time points during drugadministration. The effect of therapy is determined based on thesecomparisons. If a treatment is effective, then the one or morebiomarkers will trend toward normal, while if treatment is ineffective,the biomarkers will trend toward disease indications. If a treatment iseffective, then the one or more biomarkers will trend toward normal,while if treatment is ineffective, the one or more biomarkers will trendtoward disease indications.

6. Generation of Classification Algorithms for Qualifying Ovarian CancerStatus

In some embodiments, data derived from the spectra (e.g., mass spectraor time-of-flight spectra) that are generated using samples such as“known samples” can then be used to “train” a classification model. A“known sample” is a sample that has been pre-classified. The data thatare derived from the spectra and are used to form the classificationmodel can be referred to as a “training data set.” Once trained, theclassification model can recognize patterns in data derived from spectragenerated using unknown samples. The classification model can then beused to classify the unknown samples into classes. This can be useful,for example, in predicting whether or not a particular biological sampleis associated with a certain biological condition (e.g., diseased versusnon-diseased).

The training data set that is used to form the classification model maycomprise raw data or pre-processed data. In some embodiments, raw datacan be obtained directly from time-of-flight spectra or mass spectra,and then may be optionally “pre-processed” as described above.

Classification models can be formed using any suitable statisticalclassification (or “learning”) method that attempts to segregate bodiesof data into classes based on objective parameters present in the data.Classification methods may be either supervised or unsupervised.Examples of supervised and unsupervised classification processes aredescribed in Jain, “Statistical Pattern Recognition: A Review”, IEEETransactions on Pattern Analysis and Machine Intelligence, Vol. 22, No.1, January 2000, the teachings of which are incorporated by reference.

In supervised classification, training data containing examples of knowncategories are presented to a learning mechanism, which learns one ormore sets of relationships that define each of the known classes. Newdata may then be applied to the learning mechanism, which thenclassifies the new data using the learned relationships. Examples ofsupervised classification processes include linear regression processes(e.g., multiple linear regression (MLR), partial least squares (PLS)regression and principal components regression (PCR)), binary decisiontrees (e.g., recursive partitioning processes such asCART—classification and regression trees), artificial neural networkssuch as back propagation networks, discriminant analyses (e.g., Bayesianclassifier or Fischer analysis), logistic classifiers, and supportvector classifiers (support vector machines).

A preferred supervised classification method is a recursive partitioningprocess. Recursive partitioning processes use recursive partitioningtrees to classify spectra derived from unknown samples. Further detailsabout recursive partitioning processes are provided in U.S. PatentApplication No. 2002 0138208 A1 to Paulse et al., “Method for analyzingmass spectra.”

In other embodiments, the classification models that are created can beformed using unsupervised learning methods. Unsupervised classificationattempts to learn classifications based on similarities in the trainingdata set, without pre-classifying the spectra from which the trainingdata set was derived. Unsupervised learning methods include clusteranalyses. A cluster analysis attempts to divide the data into “clusters”or groups that ideally should have members that are very similar to eachother, and very dissimilar to members of other clusters. Similarity isthen measured using some distance metric, which measures the distancebetween data items, and clusters together data items that are closer toeach other. Clustering techniques include the MacQueen's K-meansalgorithm and the Kohonen's Self-Organizing Map algorithm.

Learning algorithms asserted for use in classifying biologicalinformation are described, for example, in PCT International PublicationNo. WO 01/31580 (Barnhill et al., “Methods and devices for identifyingpatterns in biological systems and methods of use thereof”), U.S. PatentApplication No. 2002 0193950 A1 (Gavin et al., “Method or analyzing massspectra”), U.S. Patent Application No. 2003 0004402 A1 (Hitt et al.,“Process for discriminating between biological states based on hiddenpatterns from biological data”), and U.S. Patent Application No. 20030055615 A1 (Zhang and Zhang, “Systems and methods for processingbiological expression data”).

The classification models can be formed on and used on any suitabledigital computer. Suitable digital computers include micro, mini, orlarge computers using any standard or specialized operating system, suchas a Unix, Windows™ or Linux™ based operating system. The digitalcomputer that is used may be physically separate from the massspectrometer that is used to create the spectra of interest, or it maybe coupled to the mass spectrometer.

The training data set and the classification models according toembodiments of the invention can be embodied by computer code that isexecuted or used by a digital computer. The computer code can be storedon any suitable computer readable media including optical or magneticdisks, sticks, tapes, etc., and can be written in any suitable computerprogramming language including C, C++, visual basic, etc.

The learning algorithms described above are useful both for developingclassification algorithms for the biomarkers already discovered, or forfinding new biomarkers for ovarian cancer. The classificationalgorithms, in turn, form the base for diagnostic tests by providingdiagnostic values (e.g., cut-off points) for biomarkers used singly orin combination.

7. Compositions of Matter

In another aspect, this invention provides compositions of matter basedon the biomarker of this invention.

In one embodiment, this invention provides a biomarker of this inventionin purified form. Purified biomarkers have utility as antigens to raiseantibodies. Purified biomarkers also have utility as standards in assayprocedures. As used herein, a “purified biomarker” is a biomarker thathas been isolated from other proteins and peptides, and/or othermaterial from the biological sample in which the biomarker is found.Biomarkers may be purified using any method known in the art, including,but not limited to, mechanical separation (e.g., centrifugation),ammonium sulphate precipitation, dialysis (including size-exclusiondialysis), size-exclusion chromatography, affinity chromatography,anion-exchange chromatography, cation-exchange chromatography, andmethal-chelate chrmatography. Such methods may be performed at anyappropriate scale, for example, in a chromatography column, or on abiochip.

In another embodiment, this invention provides a biospecific capturereagent, optionally in purified form, that specifically binds abiomarker of this invention. In one embodiment, the biospecific capturereagent is an antibody. Such compositions are useful for detecting thebiomarker in a detection assay, e.g., for diagnostics.

In another embodiment, this invention provides an article comprising abiospecific capture reagent that binds a biomarker of this invention,wherein the reagent is bound to a solid phase. For example, thisinvention contemplates a device comprising bead, chip, membrane,monolith or microtiter plate derivatized with the biospecific capturereagent. Such articles are useful in biomarker detection assays.

In another aspect this invention provides a composition comprising abiospecific capture reagent, such as an antibody, bound to a biomarkerof this invention, the composition optionally being in purified form.Such compositions are useful for purifying the biomarker or in assaysfor detecting the biomarker.

In another embodiment, this invention provides an article comprising asolid substrate to which is attached an adsorbent, e.g., achromatographic adsorbent or a biospecific capture reagent, to which isfurther bound a biomarker of this invention. In one embodiment, thearticle is a biochip or a probe for mass spectrometry, e.g., a SELDIprobe. Such articles are useful for purifying the biomarker or detectingthe biomarker.

8. Kits for Detection of Biomarkers for Ovarian Cancer

In another aspect, the present invention provides kits for qualifyingovarian cancer status, which kits are used to detect the biomarkeraccording to the invention. In one embodiment, the kit comprises a solidsupport, such as a chip, a microtiter plate or a bead or resin having acapture reagent attached thereon, wherein the capture reagent binds abiomarker of the invention. Thus, for example, the kits of the presentinvention can comprise mass spectrometry probes for SELDI, such asProteinChip® arrays. In the case of biospecfic capture reagents, the kitcan comprise a solid support with a reactive surface, and a containercomprising the biospecific capture reagent.

The kit can also comprise a washing solution or instructions for makinga washing solution, in which the combination of the capture reagent andthe washing solution allows capture of the biomarker or biomarkers onthe solid support for subsequent detection by, e.g., mass spectrometry.The kit may include more than type of adsorbent, each present on adifferent solid support.

In a further embodiment, such a kit can comprise instructions forsuitable operational parameters in the form of a label or separateinsert. For example, the instructions may inform a consumer about how tocollect the sample, how to wash the probe or the particular biomarkersto be detected.

In yet another embodiment, the kit can comprise one or more containerswith biomarker samples, to be used as standard(s) for calibration.

9. Determining Therapeutic Efficacy of Pharmaceutical Drug

In another embodiment, this invention provides methods for determiningthe therapeutic efficacy of a pharmaceutical drug. These methods areuseful in performing clinical trials of the drug, as well as monitoringthe progress of a patient on the drug. Therapy or clinical trialsinvolve administering the drug in a particular regimen. The regimen mayinvolve a single dose of the drug or multiple doses of the drug overtime. The doctor or clinical researcher monitors the effect of the drugon the patient or subject over the course of administration. If the drughas a pharmacological impact on the condition, the amounts or relativeamounts (e.g., the pattern or profile) of the biomarkers of thisinvention changes toward a non-disease profile. For example, hepcidin isincreased with disease, while transthyretin is decreased in disease.Therefore, one can follow the course of the amounts of these biomarkersin the subject during the course of treatment. Accordingly, this methodinvolves measuring one or more biomarkers in a subject receiving drugtherapy, and correlating the amounts of the biomarkers with the diseasestatus of the subject. One embodiment of this method involvesdetermining the levels of the biomarkers for at least two different timepoints during a course of drug therapy, e.g., a first time and a secondtime, and comparing the change in amounts of the biomarkers, if any. Forexample, the biomarkers can be measured before and after drugadministration or at two different time points during drugadministration. The effect of therapy is determined based on thesecomparisons. If a treatment is effective, then the biomarkers will trendtoward normal, while if treatment is ineffective, the biomarkers willtrend toward disease indications. If a treatment is effective, then thebiomarkers will trend toward normal, while if treatment is ineffective,the biomarkers will trend toward disease indications.

10. Use of Biomarkers for Ovarian Cancer in Screening Assays and Methodsof Treating Ovarian Cancer

The methods of the present invention have other applications as well.For example, the biomarker can be used to screen for compounds thatmodulate the expression of the biomarker in vitro or in vivo, whichcompounds in turn may be useful in treating or preventing ovarian cancerin patients. In another example, the biomarkers can be used to monitorthe response to treatments for ovarian cancer. In yet another example,the biomarkers can be used in heredity studies to determine if thesubject is at risk for developing ovarian cancer.

Thus, for example, the kits of this invention could include a solidsubstrate having a hydrophobic function, such as a protein biochip(e.g., a Ciphergen H50 ProteinChip array, e.g., ProteinChip array) and asodium acetate buffer for washing the substrate, as well as instructionsproviding a protocol to measure the biomarkers of this invention on thechip and to use these measurements to diagnose ovarian cancer.

Compounds suitable for therapeutic testing may be screened initially byidentifying compounds which interact with one or more CTAP3-relatedproteins. By way of example, screening might include recombinantlyexpressing a CTAP3-related protein, e.g., CTAP3, purifying thebiomarker, and affixing the biomarker to a substrate. Test compoundswould then be contacted with the substrate, typically in aqueousconditions, and interactions between the test compound and the biomarkerare measured, for example, by measuring elution rates as a function ofsalt concentration. Certain proteins may recognize and cleaveCTAP3-related proteins, in which case the proteins may be detected bymonitoring the digestion of one or more biomarkers in a standard assay,e.g., by gel electrophoresis of the proteins.

In a related embodiment, the ability of a test compound to inhibit theactivity of one or more of the CTAP3-related proteins may be measured.One of skill in the art will recognize that the techniques used tomeasure the activity of a particular biomarker will vary depending onthe function and properties of the biomarker. For example, an enzymaticactivity of a biomarker may be assayed provided that an appropriatesubstrate is available and provided that the concentration of thesubstrate or the appearance of the reaction product is readilymeasurable. The ability of potentially therapeutic test compounds toinhibit or enhance the activity of a given biomarker may be determinedby measuring the rates of catalysis in the presence or absence of thetest compounds. The ability of a test compound to interfere with anon-enzymatic (e.g., structural) function or activity of a CTAP3-relatedproteins may also be measured. For example, the self-assembly of amulti-protein complex which includes one of the CTAP3-related proteinsmay be monitored by spectroscopy in the presence or absence of a testcompound. Alternatively, if the biomarker is a non-enzymatic enhancer oftranscription, test compounds which interfere with the ability of thebiomarker to enhance transcription may be identified by measuring thelevels of biomarker-dependent transcription in vivo or in vitro in thepresence and absence of the test compound.

Test compounds capable of modulating the activity of a CTAP3-relatedprotein may be administered to patients who are suffering from or are atrisk of developing ovarian cancer or other cancer. For example, theadministration of a test compound which increases the activity of aparticular biomarker may decrease the risk of ovarian cancer in apatient if the activity of the particular biomarker in vivo prevents theaccumulation of proteins for ovarian cancer. Conversely, theadministration of a test compound which decreases the activity of aparticular biomarker may decrease the risk of ovarian cancer in apatient if the increased activity of the biomarker is responsible, atleast in part, for the onset of ovarian cancer.

In an additional aspect, the invention provides a method for identifyingcompounds useful for the treatment of disorders such as ovarian cancerwhich are associated with increased levels of modified forms of CTAP3.For example, in one embodiment, cell extracts or expression librariesmay be screened for compounds which catalyze the cleavage of full-lengthCTAP3 to form truncated forms of CTAP3. In one embodiment of such ascreening assay, cleavage of CTAP3 may be detected by attaching afluorophore to CTAP3 which remains quenched when CTAP3 is uncleaved butwhich fluoresces when the protein is cleaved. Alternatively, a versionof full-length CTAP3 modified so as to render the amide bond betweenamino acids x and y uncleavable may be used to selectively bind or“trap” the cellular protesase which cleaves full-length CTAP3 at thatsite in vivo. Methods for screening and identifying proteases and theirtargets are well-documented in the scientific literature, e.g., inLopez-Ottin et al. (Nature Reviews, 3:509-519 (2002)).

In yet another embodiment, the invention provides a method for treatingor reducing the progression or likelihood of a disease, e.g., ovariancancer, which is associated with the increased levels of truncatedCTAP3. For example, after one or more proteins have been identifiedwhich cleave full-length CTAP3, combinatorial libraries may be screenedfor compounds which inhibit the cleavage activity of the identifiedproteins. Methods of screening chemical libraries for such compounds arewell-known in art. See, e.g., Lopez-Otin et al. (2002). Alternatively,inhibitory compounds may be intelligently designed based on thestructure of CTAP3.

N-terminal truncations of CTAP3 are thought to diminish CTAP3's proteaseinhibitory activity. See, e.g., Abrahamson et al. (Biochem. J.273:621-626 (1991)). Compounds which impart truncated CTAP3 with thefunctionality of full-length CTAP3 are likely therefore to be useful intreating conditions, such as ovarian cancer, which are associated withthe truncated form of CTAP3. Therefore, in a further embodiment, theinvention provides methods for identifying compounds which increase theaffinity of truncated CTAP3 for its target proteases. For example,compounds may be screened for their ability to impart truncated CTAP3with the protease inhibitory activity of full-length CTAP3. Testcompounds capable of modulating the inhibitory activity of CTAP3 or theactivity of molecules which interact with CTAP3 may then be tested invivo for their ability to slow or stop the progression of ovarian cancerin a subject. One of ordinary skill in the art would understand that themethods exemplified above using CTAP3 are applicable to any of theCTAP3-related proteins described herein.

At the clinical level, screening a test compound includes obtainingsamples from test subjects before and after the subjects have beenexposed to a test compound. The levels in the samples of one or more ofthe CTAP3-related proteins, e.g., CTAP3, 2 may be measured and analyzedto determine whether the levels of the biomarkers change after exposureto a test compound. The samples may be analyzed by mass spectrometry, asdescribed herein, or the samples may be analyzed by any appropriatemeans known to one of skill in the art. For example, the levels of aCTAP3-related proteins may be measured directly by Western blot usingradio- or fluorescently-labeled antibodies which specifically bind tothe biomarkers. Alternatively, changes in the levels of mRNA encodingthe one or more biomarkers may be measured and correlated with theadministration of a given test compound to a subject. In a furtherembodiment, the changes in the level of expression of one or more of thebiomarkers may be measured using in vitro methods and materials. Forexample, human tissue cultured cells which express, or are capable ofexpressing, one or more of the CTAP3-related proteins may be contactedwith test compounds. Subjects who have been treated with test compoundswill be routinely examined for any physiological effects which mayresult from the treatment. In particular, the test compounds will beevaluated for their ability to decrease disease likelihood in a subject.Alternatively, if the test compounds are administered to subjects whohave previously been diagnosed with ovarian cancer, test compounds willbe screened for their ability to slow or stop the progression of thedisease.

11. Examples 11.1. Example 1 Discovery of a biomarker for Ovarian CancerExample 1

Profiling Methods:

Serum fractionation: 25 ul of supernatant were mixed with 37.5 ul of adenaturing buffer (U9: 9 M urea, 2% CHAPS, 50 mM Tris pH 9.0) andvortexed for 30 minutes at 4 degrees. Add 37.5 ul of 50 mM Tris (pH9) togive a total volume of 100 ul. For each sample, 100 ul of Q CeramicHyperD 20 anion exchange resin as 50% suspension was equilibrated in 100ul of 50 mM Tris (pH9) first, then Ul buffer (U9 that was diluted 1:9 in50 mM Tris pH 9.0) three times. 100 ul of the denatured serum wasapplied to the resin and allowed to bind for thirty minutes at 4degrees. The unbound material was collected and then 75 ul of washbuffer 1 (50 mM Tris-HCl+0.1% OGP+50 mM Sodium Chloride, pH 9) was addedto the resin. The resin was agitated for 10 minutes on a Micromix. Thiswash was collected and combined with the unbound material (flow through;fraction 1). Fractions were then collected in a stepwise pH gradientusing two times 75 ul each aliquots of wash buffers at pH 7, 5, 4, 3,and organic solvent. Each time the resin was agitated for 10 minutes ona Micromix. This led to the collection of a total of six fractions. Thebuffers are as follows: Wash Buffer 2: 50 mM HEPES+0.1% OGP 50 mM SodiumChloride (pH 7); Wash Buffer 3: 100 mM Sodium Acetate+0.1% OGP+50 mMSodium Chloride (pH 5); Wash Buffer 4: 100 mM Sodium Acetate+0.1% OGP+50mM Sodium Chloride (pH 4); Wash Buffer 5: 50 mM Sodium Citrate+0.1%OGP+50 mM Sodium Chloride (pH 3); Wash Buffer 6: 33.3% 2-propanol/16.7%acetonitrile/0.1% trifluoroacetic acid. Fractionation was performed on aTecan Aquurius 96 (Tecan) and a Micromix shaker (DPC). A sample ofcontrol pooled human serum (Intergen) was processed identically in onewell of each column of samples.

Chip Binding:

20 ul of each fraction was first pH adjusted with 20 ul of differentbuffers and then bound to IMAC and CM10 ProteinChip arrays. For IMACarrays, the spots were charged with copper and rinsed and equilibrated.Fractions 1 and 2 were mixed with 20 ul of IMAC binding buffer (100 mMsodium phosphate pH 7.0 containing 500 mM NaCl); fractions 3-6 weremixed with 100 mM Tris HCl pH 10. For CM10, fractions 1, 2 and 3 weremixed with 20 ul of 100 mM acetic acid; fractions 4, 5 and 6 were mixedwith 20 ul of CM10 binding buffer (100 mM Na Acetate, pH 4.0). Bindingwas allowed to occur for 120 minutes at room temperature. Chips werethen washed two times with 150 ul binding buffer and then twice with 200ul water. The matrix used was SPA (add 400 ul of 50% acetonitrile and0.5% TFA to one tube, mix 5 minutes). Each spot was deposited with 1 ulof matrix twice. Chip binding was performed on a Tecan Aquurius 96(Tecan) and a Micromix shaker (DPC).

Data Acquisition and Analysis:

ProteinChip arrays were read on PCS4000 instruments usingCiphergenExpress software version 3.0. Instruments were monitored weeklyfor performance using insulin and immunoglobulin standards. Each chipwas read at two laser energies, low and high. Spectra were organized andbaseline subtracted. Spectra were externally calibrated using a set ofcalibrants. Spectra were then normalized to total ion current accordingto the following parameters: for chips containing SPA, the low energystarting mass was 2000 M/Z; the high energy starting mass was 10000 M/Z.For peak clustering, the signal to noise ratio was set at 3.

Example 2 Chromatographic Assay of Ovarian Cancer Markers

Add 50 ul 50% suspension of IDA-Ni (II) beads (Biosepra IMAC Hypercel,charged with 0.1M NiSO4) to 96-well filter plate. Transfer IDA-Ni slurryto a plastic beaker and keep slurry well mixed by hand or on magneticstir plate at low speed during dispensing. Use pipet tips with largeorifice to dispense beads.

Wash beads three times, each with 200 ul 0.02% (w/v) Triton X100 PBS(2×). 5 ul serum+7.5 ul 9M urea 2% (w/v) CHAPS 50 mM Tris HCl pH9 inv-bottom 96-well plate, RT vortex 2 min.

Dilute with 150 ul 0.02% (w/v) Triton X100 PBS (2×) with proteaseinhibitor cocktail (Roche, no EDTA, 1 tablet per 50 ml).

Add to IDA-Ni plate, RT shake for 30 min on Micromix shaker (settings:15,6,30).

Vacuum filter on vacuum manifold.

Wash plate with 200 ul of 0.02% TX100 PBS (2×) eight times, no mixing.

Gently blot dry bottom of filter plate on Kimwipe (remember to dry edgesof filter membrane).

Elute with 75 ul 10 mM imidazole 1M urea 0.1% (w/v) CHAPS 0.3M KCl 100mM TrisHCl pH7.5 four times, mix 10 min each time (15,6,10). Vacuumfilter to collect in 0.45 ml v-bottom 96-well plate.

IMAC30 Chip Binding in Bioprocessor:

Add 50 ul 50 mM CuSO4 to each well. Shake for 10 min on Micromix(15,5,10).

Empty wells. Add 150 ul water and empty wells.

Add 50 ul 50 mM NaOAc pH4 to each well. Shake for 5 min.

Empty wells. Add 150 ul water and empty wells.

Equilibrate 2 times 200 ul μM urea 0.1% CHAPS 0.3M KCl 100 mM Tris HClpH7.5.

Shake for 5 min each (15,5,5) on Micromix.

Mix eluate plate at low speed for 1 minute on Micromix.

Add 40 ul of eluate to 150 ul (final imidazole 2.1 mM) of 1M urea 0.1%CHAPS 0.3M KCl 100 mM Tris HCl pH7.5 on IMAC30-Cu (II) chip. Seal withtape and vortex 60 min (15,5,60) at RT.

Wash 1 time with 200 ul μM urea 0.1% (w/v) CHAPS 0.3M KCl 50 mM TrisHClpH7.5, mix 5 min.

Wash 2 times with 200 ul water, mix 1 min each.

Add 2 times 1 ul sinapinic acid. 1 tube SPA+200 ul ACN+200 ul 1% TFA.

Read chips using low laser intensity. Focus at 14 KDa.

Q10 Chip Binding in Bioprocessor:

Equilibrate 2 times 200 ul 0.1M sodium phosphate buffer pH7.5. Shake for5 min each (15,5,5).

Mix eluate plate at low speed for 1 minute on Micromix.

Add 40 ul of eluate to 150 ul (final imidazole 2.1 mM) of 0.1M sodiumphosphate buffer pH7.5 on Q10 chip. Seal with tape and vortex 60 min(15,5,60) at RT.

Wash 2 times with 200 ul 0.1M sodium phosphate pH7.5, mix 5 min each.

Wash 1 time with 200 ul water, mix 1 min.

Add 2 times 1 ul sinapinic acid. 1 tube SPA+200 ul ACN+200 ul 1% TFA.

Read chips using low and high laser intensity. Focus at 14 KDa.

Preparation of IDA-Ni Beads:

Measure 100 ml IMAC Hypercel (Biosepra) packed gel in a graduatedcylinder.

Transfer to a filter unit (0.45 μm cellulose acetate). Wash beads with500 ml water.

Transfer packed beads to a 500 ml round bottle.

Add 100 ml 0.1M NiSO₄ to beads and mix on rotator for 2 hour at RT.

Wash beads with 1000 ml water in filter unit.

Wash with 500 ml 2×PBS pH7.2.

Store IDA-Ni beads in 2×PBS pH7.2 as 50% slurry at 4° C.

Materials and Reagents:

IMAC Hypercel (Biosepra)

Pipet tips with large orifice 1-200 ul (VWR 53503-612)

NiSO4.7H2O

PBS pH7.2, 10× (GIBCO, dilute to 2×)

Urea

CHAPS (prepare 10% (w/v) CHAPS stock solution in water)Tris base (to prepare U9CHAPS TrisHCl pH9)HCl for adjusting pH of Tris baseTriton X100 (prepare 1% (w/v) TX100 stock solution in water, dilute in2×PBS to make 0.02%)

Complete protease inhibitor cocktail tablets, EDTA-free (Roche, 1 873580)

Silent Screen filter plate 96 well, Loprodyne membrane 1.2 μm pore(Nalge Nunc, 256065)

Vacuum manifold for 96-well plates

Imidazole KCl 1M Tris HCl pH7.5 (Invitrogen) CUSO₄.5H₂O

Sodium acetate and acetic acid (to make 50 mM sodium acetate buffer pH4)Sodium phosphate monobasic and dibasic (to make 0.1M sodium phosphatebuffer pH7.5)Sinapinic acid (Ciphergen Biosystems)

Acetonitrile TFA

IMAC30 chipsQ10 chips

It is understood that the examples and embodiments described herein arefor illustrative purposes only and that various modifications or changesin light thereof will be suggested to persons skilled in the art and areto be included within the spirit and purview of this application andscope of the appended claims. All publications, patents, and patentapplications cited herein are hereby incorporated by reference in theirentirety for all purposes.

1. A method for qualifying ovarian cancer status in a subjectcomprising: (a) measuring at least one biomarker including aCTAP3-related protein in a biological sample from the subject; and (b)correlating the measurement with ovarian cancer status.
 2. The method ofclaim 1, wherein the CTAP3-related protein is CTAP3 (residues 44-128 ofSEQ ID NO:1).
 3. The method of claim 2 wherein CTAP3 is measured bycapturing the biomarker on an adsorbent surface of a SELDI probe anddetecting the captured biomarkers by laser desorption-ionization massspectrometry.
 4. The method of claim 2 wherein CTAP3 is measured byimmunoassay.
 5. The method of claim 2 wherein the sample is serum. 6.The method of claim 2 wherein the correlating is performed by a softwareclassification algorithm.
 7. The method of claim 2 wherein ovariancancer status is selected from ovarian cancer and non-ovarian cancer. 8.The method of claim 2 wherein ovarian cancer status is selected fromearly stage and late stage
 2. 9. The method of claim 2, furthercomprising: (c) reporting the status to the subject.
 10. The method ofclaim 2, further comprising: (c) recording the status on a tangiblemedium.
 11. The method of claim 2, further comprising: (c) managingsubject treatment based on the status.
 12. The method of claim 11,further comprising: (d) measuring CTAP3 after managing treatment andcorrelating the measurement with disease progression.
 13. The method ofclaim 3, wherein the adsorbent is an IMAC copper adsorbent or abiospecific adsorbent.
 14. (canceled)
 15. The method of claim 2, furthercomprising measuring and correlating at least one biomarker selectedfrom the group consisting of CA125, transferrin, haptoglobin, ApoA1,transthyretin, ITIH4 internal fragment, beta 2-microglobulin, hepcidin,prostatin, osteopontin, esoinophil-derived neurotoxin, leptin,prolactin, IGF-II, hemoglobin and modified forms thereof.
 16. The methodof claim 2, further comprising measuring and correlating at least onebiomarker selected from the group consisting of CA125 II, CA15-3,CA19-9, CA72-4, CA 195, tumor associated trypsin inhibitor (TATI), CEA,placental alkaline phosphatase (PLAP), Sialyl TN, galactosyltransferase,macrophage colony stimulating factor (M-CSF, CSF-1), lysophosphatidicacid (LPA), 110 kD component of the extracellular domain of theepidermal growth factor receptor (p110EGFR), tissue kallikreins, e.g.,kallikrein 6 and kallikrein 10 (NES-1), prostasin, HE4, creatine kinaseB (CKB), LASA, HER-2/neu, urinary gonadotropin peptide, Dianon NB 70/K,Tissue peptide antigen (TPA), SMRP, osteopontin, and haptoglobin,leptin, prolactin, insulin-like growth factor I and insulin-like growthfactor II.
 17. A method for determining the course of ovarian cancercomprising: (a) measuring, at a first time, at least one biomarkerincluding a CTAP3-related protein in a biological sample from thesubject; (b) measuring, at a second time, the CTAP3-related protein in abiological sample from the subject; and (c) comparing the firstmeasurement and the second measurement; wherein the comparativemeasurements determine the course of the ovarian cancer.
 18. The methodof claim 17, wherein the CTAP3-related protein is CTAP3 (amino acidresidues 44-128 of SEQ ID NO:1).
 19. A kit comprising: (a) a solidsupport comprising at least one capture reagent attached thereto,wherein the capture reagent binds to a CTAP3-related protein; and (b)instructions for using the solid support to detect the CTAP3-relatedprotein.
 20. The kit of claim 19, wherein the CTAP3-related protein isCTAP3 (amino acid residues 44-128 of SEQ ID NO:1).
 21. The kit of claim19, wherein the solid support comprising a capture reagent is a SELDIprobe. 22.-35. (canceled)